[SunSi12138]

Closes #589

Audit boundary

The repository currently has no SharpLink-owned ActivityEvent emission sites, so this PR does not invent a parallel diagnostic event stream. OpenTelemetry sampler/exporter/provider ownership and the stable SharpLink.Client, SharpLink.Server, and SharpLink source/meter identities remain unchanged.

Runtime policy

Adds one immutable SharpLink-owned telemetry detail generation on both Client and Server.

• Detailed is the default and preserves the historical telemetry surface.
• Basic retains logical call activities, stable RPC identity tags, core metrics, and bounded resource-exhaustion classification.
• Basic suppresses existing optional diagnostic/high-cardinality trace detail: Server request identity, Client lifetime-source enrichment, and retry-attempt child activities.
• Client captures the detail generation once at the logical-call creation boundary in ResolvedCallControl; interceptor suspension, delayed stream enumeration, retry backoff, and later retry attempts therefore cannot mix detail generations within one logical RPC.
• Server captures the current generation at the call telemetry start boundary.
• updates are atomic control-path publications and are rejected once drain/stop/fault begins.

Ownership boundary

This API does not implement or replace OpenTelemetry sampling, exporters, processors/providers, resource configuration, or listener lifecycle. It does not replace/rename ActivitySource, Meter, or metric instruments. doc/observability.md documents this boundary explicitly.

Regression coverage

SharpLinkRuntimeTelemetryDetailPolicyTests covers:

• Detailed -> Basic publication and same-value no-op;
• invalid candidate rollback and Client Stop sealing;
• Server Detailed request identity versus Basic omission while stable RPC tags remain;
• a Client logical call captured as Basic remaining Basic after the live policy changes to Detailed;
• Basic retry attempts preserving the prior ambient Activity.Current and emitting no attempt child Activity;
• future Detailed calls emitting retry-attempt activities and restoring ambient context on completion.

Branch head: 94a60fb977b76af1cbef18a3b3021965d0d1dde1.
Validated target: dev@3bccdefd75fbb1f7e04ad6816f615d198004230e.

Validation

• PR Fast 34192031561: PASS.
• ready-state PR Fast 34192220272: PASS.
• CodeQL 34192031623: PASS.
• PR Extended 34192232906: PASS — Debug/Release builds, Integration Tests, NativeAOT transport/topology smoke, package contract verification/smoke, demo/load smoke, and the complete six-platform desktop codec compatibility matrix.

The first Windows ARM codec producer attempt hit a hosted-runner .NET setup CLR internal error (0x80131506) before project execution. The failed jobs were rerun on the identical PR merge ref; Windows ARM production/verification and the final codec/Extended summaries then passed.